Methods and apparatus for aiding the operator in the metering process have previously been proposed. For example, German Published Application No 25 36 045 describes a balance which has a non-numeric display in addition to the conventional numeric display. The non-numeric display furnishes an indication of the still available weight range or, alternatively, of the weight range already used. German Pat. No. 26 04 747 describes a similar balance in which strips of light emitting elements arranged in the forms of symbols are used. However, none of the known balances are suitable as an aid to the operator during a metering process unless, coincidently, the desired weight is the same as the maximum value accommodated by the balance.
U.S. Pat. No. 4,200,896 discloses a seven segment display in which only the horizontal segments are activated when a non-numeric display is desired. In this display, the operator derives information as to the amount of the substance on the balance by the position of the horizontal segments. This method has the advantage that a separate additional display is not required. However it has the disadvantage that the display takes place in fixed decimal steps. In addition, it requires a higher concentration on the part of the operator because the metering process must be fitted to the logarithmic rate of change of the display. These remarks also apply to another known method (disclosed in German Published Application No. 27 02 842) which also operates in fixed decimal steps, but wherein a numeric display is used in addition to a non-numeric display utilizing light emitting elements.